Chen L, Xin X, Eckhart A D, Yang N, Faber J E
Department of Physiology, University of North Carolina, Chapel Hill 27599-7545, USA.
J Biol Chem. 1995 Dec 29;270(52):30980-8. doi: 10.1074/jbc.270.52.30980.
Rat aorta smooth muscle cells which express all three alpha 1-adrenoreceptors (alpha 1A, alpha 1B and alpha 1D) were used to determine the effect of stimulation of alpha 1-adrenergic receptor subtypes on cell growth. "Combined" alpha 1-adrenoreceptor subtype stimulation with norepinephrine alone caused a concentration-dependent, prazosin-sensitive increase in protein content and synthesis: 48 h of stimulation at 1 microM increased cell protein to 216 +/- 40% of time-matched controls (p = 0.008) and RNA to 140 +/- 13% (p = 0.03); protein synthesis increased to 167 +/- 13% (p < 0.01) after 24 h. Stimulation with norepinephrine plus the selective alpha 1A/alpha 1D antagonist 5-methylurapidil produced greater increases in alpha-actin mRNA (270 +/- 40% at 8 h; p = 0.007), total cell protein (220 +/- 45% at 24 h; p = 0.004), and RNA (135 +/- 8% at 24 h; p = 0.01). These effects were prevented by pretreatment with the selective alpha 1B antagonist chloroethylclonidine. Comparable results were obtained for intact aortae. Stimulation with norepinephrine plus 5-methylurapidil increased (p < 0.05) tissue protein, RNA, dry weight, and alpha-actin mRNA; and as in culture cells, combined stimulation with norepinephrine alone attenuated these responses. By comparison, adventitia (fibroblasts) was unaffected. Removal of endothelial cells had no effect. alpha 1B mRNA decreased by 42 +/- 12% (p = 0.01) in cultured cells during combined alpha 1-adrenoreceptor stimulation and by 23 +/- 8% (p = 0.03) for intact aorta. alpha 1D and beta-actin mRNA were unchanged in cultured cells, aorta media, and adventitia. These findings suggest that prolonged stimulation of chloroethylclonidine-sensitive, possibly alpha 1B-adrenoceptors induces hypertrophy of arterial smooth muscle cells and that stimulation of 5-methylurapidil-sensitive, non-alpha 1B-adrenoreceptors attenuates this growth response.
采用表达所有三种α1 - 肾上腺素能受体（α1A、α1B和α1D）的大鼠主动脉平滑肌细胞来确定刺激α1 - 肾上腺素能受体亚型对细胞生长的影响。单独用去甲肾上腺素进行“联合”α1 - 肾上腺素能受体亚型刺激导致蛋白质含量和合成呈浓度依赖性、对哌唑嗪敏感的增加：在1 μM刺激48小时后，细胞蛋白质增加至时间匹配对照组的216±40%（p = 0.008），RNA增加至140±13%（p = 0.03）；24小时后蛋白质合成增加至167±13%（p < 0.01）。用去甲肾上腺素加选择性α1A/α1D拮抗剂5 - 甲基尿嘧啶刺激导致α - 肌动蛋白mRNA（8小时时为270±40%；p = 0.007）、总细胞蛋白质（24小时时为220±45%；p = 0.004）和RNA（24小时时为135±8%；p = 0.01）有更大程度的增加。这些作用可通过用选择性α1B拮抗剂氯乙可乐定预处理来预防。完整主动脉也得到了类似结果。用去甲肾上腺素加5 - 甲基尿嘧啶刺激增加了（p < 0.05）组织蛋白质、RNA、干重和α - 肌动蛋白mRNA；并且与培养细胞一样，单独用去甲肾上腺素联合刺激减弱了这些反应。相比之下，外膜（成纤维细胞）未受影响。去除内皮细胞没有影响。在联合α1 - 肾上腺素能受体刺激期间，培养细胞中的α1B mRNA下降了42±12%（p = 0.01），完整主动脉中的α1B mRNA下降了23±8%（p = 0.03）。培养细胞、主动脉中膜和外膜中的α1D和β - 肌动蛋白mRNA没有变化。这些发现表明，对氯乙可乐定敏感、可能是α1B - 肾上腺素能受体的长期刺激诱导动脉平滑肌细胞肥大，而对5 - 甲基尿嘧啶敏感、非α1B - 肾上腺素能受体的刺激减弱了这种生长反应。
